Apparatus for advancing a predetermined length of strip-shaped material

ABSTRACT

An apparatus for advancing a predetermined length of strip material from a supply roll to a delivery point. In addition to strip pull-off mechanism (15) cooperating with a one-way means (20, 22) to pull-off the desired strip length from the supply roll (10), the apparatus has a gripper (26) reciprocating in synchronism and in push-pull connection with the pull-off mechanism, the gripper gripping and advancing the strip end. The strip (11) also passes a strip brake (20, 21) and a photocell (19) which on detection of a suitable mark causes the brake to be actuated to stop the strip and the gripper to be actuated so that it releases the strip. As the moving parts have a very small inertia, the braking may be effected almost instantaneously and with great precision.

The invention relates to an apparatus for advancing a predeterminedlength of strip-shaped material from a supply roll to a delivery point.Such apparatus includes a pull-off mechanism having a reciprocablepull-off means over which the strip runs, and a one-way means disposedbetween this mechanism and the delivery point, through which the stripruns.

The Danish patent specification No. 130 883 discloses an apparatus ofthis type for applying handles to parcels which are moved past insubstantially equidistant positions on a conveyor, and this apparatushas an applying means that is connected to the pull-off means and whichmoves in and out of the gap between two parcels while exerting aresilient pressure against the parcels to attach adhesive faces of thestrip to the side faces of the parcels. The apparatus also has a knifewhich on attachment of the strip moves down between the parcels and cutsthe strip length between them. The function of the apparatus thus relieson each handle having been applied to a parcel before said handle issevered from the strip.

However, it is desirable in many cases that the apparatus can deliver aready, severed handle at a delivery point where it can be held in awaiting position by a suitable holding assembly. The object of theinvention is to provide an apparatus of the present type which can solvethis task with great precision, i.e. in such a way that the severedhandle is given exactly the desired predetermined length and is placedexactly in the holding assembly.

This object is achieved by the provision of a gripper arranged to bereciprocated in synchronism with the pull-off means and, at its oneextreme position, to grip the end of the strip of material, as well as astrip brake and a detector arranged to detect a mark on the strip and inresponse thereto cause the gripper to open so as to release the strip,and the strip brake to be actuated. The detector, which may e.g. be aphotocell, can determine the strip position with an almost arbitrarilydesired precision, and the only moving parts which the detector signalis to actuate are one jaw of the gripper, the strip brake and a shortlength of the strip itself. These parts have quite a small mass so thatthe processes required to stop the strip can be effected practicallyinstantaneously.

Simple embodiments of the drive mechanisms of the pull-off means and thegripper and of means for synchronizing their movements are describedbelow.

The advantage of a further embodiment of the apparatus is that the striplength advanced per working cycle may be varied merely by displacing apneumatic cylinder and the impact point of a piston rod on a pivot arm,such adjustment having no influence on the relation between the twocontrolled movements.

Shears controlled as stated in claim 6 may expediently be used forseparating the advanced strip length from the rest of the strip.

The invention will be explained more fully below with reference to thedrawing, in which:

FIG. 1 is a diagrammatic and inclined axonometric view showing the partsof an embodiment of the apparatus of the invention which are disposedalong the strip path itself, as well as a strip roll and a strip beingadvanced;

FIG. 2 is a likewise diagrammatic and inclined axonometric view showingthe drive mechanisms of the moving parts;

FIGS. 3 and 4 are diagrammatic, inclined axonometric views showing partsof the gripper and its operating mechanism in a closed and an openstate, respectively; and

FIG. 5 is a wiring diagram of an electric circuit for the control ofcertain apparatus functions.

The parts shown in FIGS. 1 and 2 may e.g. be mounted at their respectivesides of a mounting plate, not shown. In FIG. 1 the symbol 10 designatesa roll of strip material 11 intended to form handles for application toparcels, not shown. The strip may e.g. be polypropylene with adhesive onone side to which a piece of paper 12 adheres at intervals, and thestrip is severed at the center of the adhesive sections 13 so as toimpart to each handle a non-adhesive center portion 12 and two endportions that may adhere to a parcel.

From the roll 10 the strip 11 runs over a roller 14 and from therearound a pull-off roller 15 that may be reciprocated in a rectilinearpath as indicated by a double arrow 16. From the pull-off roller 15 thestrip passes around a roller 17 and from there through a detector in theform of a light source 18 and a photocell 19 whose output signal changesupon the passage from a non-adhesive to an adhesive portion of the stripand vice versa, to a brake roller 20 firmly connected to a magnet brake21. The brake roller 20 also acts as a one-way means in cooperation withan eccentrically journalled roller 22, said rollers only permitting thestrip to move in the feeding direction. From the brake roller 20 thestrip passes through shears comprising a lower plate 23 and a knife 24pivotally mounted on the plate. A spring clip 25 keeps the stripslightly pressed against the lower plate 23. Having passed through theshears the strip reaches the delivery point of the handle, pulled by agripper 26 that can be reciprocated in a rectilinear path as indicatedby a double arrow 27. Having been severed the handle may be held in thedelivery position by means of a suitable holder whose arrangementdepends upon the mechanism used for passing on the handle to the parcelto which it is to be applied. In FIG. 1 the holder is shown as two pairsof opposite plates 28 and 29 which may be covered with thin bristles onthe sides facing each other, and the severed handle may be held betweenthem with its non-adhesive center portion 12 located between the pairsof plates 28 and 29.

In FIG. 2 the symbol 30 designates a drive cylinder with end pieces 31and 32, the rear one 32 being attached to a supporting device 33 fittedon the mounting plate such that the cylinder may be vertically adjusted.The end of the piston rod 34 of the cylinder mounts a fork 35 that gripsa pivot arm 36 and is pivotally and slidably connected to it by means ofpin 37 extending between the fork prongs and through a slot 38 in thepivot arm. The pivot arm 36 has its lower end pivotally journalled onthe mounting plate by means of a pivot 39, and its upper end pivotallyand slidably connected to a carrier block 40 by means of a pin-slotconnection, only the slot 41 of which is shown in the drawing. Thecarrier block 40 also carries the pull-off roller 15, shown in FIG. 1,on a shaft (not shown), which extends through a, horizontal slot (notshown) in the mounting plate. The carrier block 40 has attached to itthe two ends of a toothed belt 43 by means of clamping members 42, saidbelt 43 running about two toothed pulleys 44 and 45 which are disposedat the same level and have the same number of teeth.

Each of the toothed pulleys 44 and 45 is firmly connected to anothertoothed pulley 46 and 47, respectively, which has twice as many teeth asthe first-mentioned ones and about which another toothed belt 48 runswhich further runs about two lower toothed pulleys 49 and 50, betweenwhich the toothed belt 48 extends along the path of movement of thegripper 27, and its ends are secured to a carrier block 51 for thegripper by means of two clamping members 52. As shown in FIGS. 3 and 4,the gripper 26 has two jaws 53 and 54, the lower jaw 53 being firmlyconnected to the carrier block 51 in a manner not shown in detail, theupper jaw 54 being disposed on one end of a shaft 55 that is rotatablyconnected to the carrier block and extends through a, horizontal slot(not shown) in the mounting plate, and on whose end a crank arm 56 witha crank 57 is mounted. A spring (not shown) urges the crank intoengagement with the underside of a flat rail 58 extending along the pathof movement of the gripper 26 and a distance beyond it at either end.End pins 59 of the rail 58 are pivotally journalled in bearings 60. Therail 58 also extends with a sliding fit through a bushing 61 which isrotatably journalled in a downwardly extending bracket 62 on the carrierblock 51. Near its one end the rail 58 has a laterally protruding, shortarm 63 which is pivotally connected to a rod 64 which may bereciprocated a short distance by an electromagnet 65. In the positionshown in FIG. 3, the electromagnet 65 is deenergized, and the rail 58lies in a horizontal position. In the position shown in FIG. 4, theelectromagnet is energized and has turned the rail 58 through a smallangle where it has pressed the crank 57 a little downwards and thus inturn rotated the gripper shaft 55 with the upper jaw 54 to open thegripper 26.

For opening the gripper 26 just before it is to grip the strip in itsone extreme position a pawl 75 is provided at this point, said pawlbeing journalled on a pivot 74 and kept in resilient engagement with astopper 77 by a tension spring 76; at the passage of the gripper thepawl engages an inclined cam edge 78 at the end of the crank arm 56,pressing said arm down to briefly open the gripper. During the passageof the gripper in the opposite direction the end edge 79 of the crankarm pivots the pawl 75 outwardly against the action of the spring 76.

Three micro-switches 66, 67 and 68 are fitted at the pneumatic cylinder30 to control certain functions and are operated by a tube 69 which isfirmly connected to the piston rod 34 through a transom 70 and slidablyextends through a hole in a plate 71, which is supported by the frontcylinder end piece 31 and is slidable on a rod 72 secured to a plate 73on the rear cylinder end piece 32.

In FIGS. 1 and 2 the apparatus is shown in an advancing step shortlybefore the completion of it. Thus, the gripper 26 has closed about theend of the strip 11 and is moving to the left in FIG. 1 (to the right inFIG. 2) driven by the pneumatic cylinder 30 whose piston rod 34approaches its extreme position, through the pivot arm 36, the carrierblock 40 for the pull-off roller 15, the toothed belt 43, the toothedpulleys 44-47, the toothed belt 48, and the carrier block 51 for thegripper and carrying the strip. It will be seen that the pull-off roller15 moves in a direction opposite to and at half the speed of the gripper26 so that the gripper does not have to exert a greater tensile forcethan that required to overcome quite small frictional forces. In thisstate both the pull magnet 65 of the rail 58 and the magnet brake 21 aredeenergized.

The photocell 19 is so disposed that the transition from a non-adhesiveportion 12 to an adhesive portion 13 of the strip 11 reaches itsimultaneously with the arrival of the front handle portion at thedelivery point where its non-adhesive portion is located between theholders 28 and 29. When the photocell detects said transition, itcauses, (see FIG. 5) via an amplifier 80, a make contact 81 to beclosed, so that the brake magnet 65 and the pull magnet 21 connected inparallel to the magnet 65 are energized through the microswitch 67,which is a break contact, operated by the cylinder 30. The energizationof the pull magnet 21 causes the rail 58 to be pivoted about the pins 59and thus the gripper 26 to be opened in the manner described above, andthe energization of the brake magnet 21 causes the strip movement to bestopped instantaneously as the moving masses are very small and theinertia counteracting the braking is correspondingly low. The strip isstopped just before the cylinder piston reaches its most advancedposition, and thus the gripper moves on a small distance after havingreleased the strip 11. Immediately before the cylinder piston reachesits extreme advanced position the tube 69 allows the microswitch 66,which is a break contact, to be released so as to close an energizingcircuit for a magnet 82, which, in a manner (not shown) either directlyor indirectly through a valve and a pneumatic cylinder, actuates theknife 24 to sever the strip.

The apparatus is now in an extreme position in which it may remain untilan external order signal via a control valve (not shown) for thepneumatic cylinder 30 actuates it to retract the piston, or the controlvalve may be actuated via the microswitch 66 to automatically initiate anew working cycle, it being contemplated that in this case the handlejust advanced is removed immediately after it has been cut free. As soonas the piston cylinder begins its return movement to pull out a newhandle length of strip material from the supply roll 10 by means of thepull-off roller 15 and to return the gripper 26 to the new strip end inthe shears 23, 24, the switch 66 is operated by the tube 69 whichresults in the knife 24 pivoting back to the position shown in FIG. 1.When the cylinder piston has moved a certain distance, the tube 69operates the switch 67 to break the energizing circuits of the magnets21 and 65 so that the magnet brake is deactivated and the grippercloses. Shortly before the gripper arrives at the shears 23, 24 it isopened by the cooperation between the cam edge 78 and the pawl 75 in themanner described above, and immediately before it reaches its extremeposition it is closed again by its spring (not shown) so as to grip thestrip end. At the same time the microswitch 68 is actuated by the tube69 and causes, in a generally known manner, the pneumatic cylinder to bereversed so that the piston again begins moving outwards. When thegripper 26 has moved so far that the next non-adhesive region 12 on thestrip 11 has reached the photocell 19, said cell causes the contact 81to open, and not until this has taken place does the tube 69 allow theswitch 67 to close again in preparation of the energizing circuits forthe magnets 21 and 65. The apparatus is now again in the first describedstate shown in FIGS. 1 and 2.

It will be seen that the stroke of the movement of the pull-off rollerand the gripper will be changed in the same proportion by displacementof the cylinder along the supporting device 33, which results in acorresponding change of the strip length fed per cycle. Thus, adaptionto another handle length does not require the microswitches 66, 67 and68 to be adjusted or the stroke of the cylinder to be changed. The pivotaxis of the pivot arm 36 is so disposed in relation to the cylindersupporting device 33 that the center point of the handle is alwayssituated between the holders 28 and 29 irrespective of the handle lengthto which the apparatus is adjusted.

I claim:
 1. An apparatus for advancing a predetermined length of strip-shaped material from a supply roll to a delivery point, comprising: a pull-off mechanism having a reciprocable pull-off means over which the strip runs, a one-way means through which the strip runs, said one-way means being disposed between said mechanism and the delivery point, a gripper arranged to be reciprocated in synchronism with said pull-off means and, at its one extreme position, to grip the end of the strip of material, a strip brake, and a detector arranged to detect a mark on the strip and in response thereto cause the gripper to open so as to release the strip, and said strip brake to be actuated.
 2. An apparatus according to claim 1 wherein said gripper is firmly connected to a toothed belt along a section between two toothed pulleys, and wherein said pull-off means is firmly connected to another toothed belt on a section between two other toothed pulleys, and wherein said two pairs of toothed belts are coupled together through a transmission mechanism having a transmission ratio of 2:1, and drive means for one toothed belt.
 3. An apparatus according to claim 2, wherein said pulleys have shafts and wherein at least one of the shafts of the toothed pulleys of said pull-off means belt has mounted thereon another toothed pulley which is non-rotatably connected to said pull-off means pulley and has twice as many teeth as said pull-off means pulley, and about which said gripper toothed belt runs.
 4. An apparatus according to claim 2 or 3, wherein said drive means are a pneumatic cylinder with a piston rod operatively connected to one toothed belt.
 5. An apparatus according to claim 4, wherein said piston rod is pivotally connected to a pivot arm which is pivotally journalled at one end thereof and connected to a drive belt at the other end thereof such that the connection between the piston rod and the pivot arm is adjustable along said arm, and wherein said pneumatic cylinder is disposed so as to be adjustable in the plane of movement of the pivot arm substantially perpendicularly to its longitudinal axis.
 6. An apparatus according to any one of claims 1 to 3, comprising shears arranged to sever the strip, said shears being actuated just before the gripper reaches its extreme position after having released the strip. 